Nonwoven fabric and method for making same



Aug. 2, 1949. c. c. WILSON ETAL NONWOVEN FABRIC AND METHOD FOR MAKINGSAME 4 Sheets-Sheet 1 Filed Nov. l8, 1947 Charles G Wilson,[Yer-51250112 Cadd wt Denzz'l Probas 6'0 Aug. 2, 1949. c. c. WILSON ETALNONWOVEN FABRIC AND METHOD FOR MAKING SAME V 4 Sheets-Sheet 2 Filed Nov.18, 1947 g il I g g g Q g; v jrwwwtw V V I W v Ckaz-IesCH Z'lson,brscizelflcudd u Derzzz'l V'Probasco Aug. 2, 1949.

Filed NOV. 18, 1947 C. C. WILSON ET AL NONWOVEN FABRIC AND METHOD FORMAKING SAME 4 Sheets-Sheet 5 C. C. WILSON ETAL NONWOVEN FABRIC ANDMETHOD FOR MAKING SAME Aug. 2, 1949.

4 Sheets-Sheet 4 Filed Nov. 18, 1947 I I I I I I I I I I I I l I n uQrwmbom Patented Aug. 2, 1949 UNITED STATES PATENT OFFICE NONWOVENFABRIC AND METHOD FOR MAKING SAME bama

Application November 18, 1947, Serial No. 786,662

9 Claims. 1

This invention relates to unwoven fabrics; a method of forming suchfabrics, and equipment for practicing the method and producing thefabrics.

Unwoven fabrics are broadly old, but the methods and equipmentheretofore used have not produced fabric of satisfactory make-up insofaras uniformity of fabric texture and strength in all directions areconcerned.

Fabrics of this type are formed by depositing fibers drawn from anysuitable source, such as a hopper, a card, or a dofier, in randomfashion on a suitable foraminous receiving member in closely interlacedrelation, the object being to secure textural uniformity and strength inall directions. Satisfactory results cannot, however, be obtainedwithout particular attention to the removal of the fibers from thesource; their distribution on the receiving member, and, as it ispreferable in many cases, subjecting the web thus formed to a bondingtreatment to stabilize the fibers and produce a web of proper density,uniformity, and stability, insofar as fiber relations are concerned.

In unwoven webs of the prior art, the fibers have been in some instancesso laid as to parallel them either warpwise or fillingwise, resulting ina fabric of unequal strength in different directions as distinguishedfrom the fabric of the present invention, in which the fibers aredisposed in uniformly random fashion, free from knots or tangles, sothat textural uniformity in all directions results.

It has been proposed in earlier methods to subject fibers to aircurrents in disposing them on a receiving surface, but such methods lackthe technical emciency of the present method, which involves the removalof the fibers directly from the supply by positive and direct aircurrents regulated within suitable ranges, insofar as intensity of flowis concerned, critical flow intensities being determined by theparticular conditions met.

In practicing the invention herein disclosed, it has been found that thespeed of the fiber carrying instrumentality which, in the presentdisclosure, is a doffer, must be considerably increased over the normalspeeds in equipment of this kind as heretofore developed, the reason forthis increased speed being that the fibers will be more completely anduniformly separated on the dofier and the knots and tangles straightenedout, so that delivery from the fiber-carrying instrumentality to thefiber-receiving and web-forming instrumentalities results in a web ofmore uniform density and strength than under the slow speed equipmentheretofore used.

Following fiber removal from the dofier, which is here shown as thesource of the raw material, by air currents, such fibers, in suspendedcondition and in free relation to one another. are carried at high speedthrough a fiber transfer duct which leads to a movable fiber receivingmember, here shown as a screen cylinder, upon which the fibers are laidin random fashion and in losely matted relation. The thickness of theweb, following the method and using the equipment hereinafter described,may be readily varied by regulating the speed of the movablefiber-receiving members so as to permit greater or less amounts of fiberto be deposited in a given period of time. Further, the width of thewebs formed on the receiving surface may be varied so as to form a webof a width equal to the full length of the fiber receiving member, orfibers may be deposited on the receiving member in less than the fulllength of that member so as to form narrow webs or slivers. As stated,the present disclosure shows the removal of fibers directly from adofier by air currents, the dotfer being supplied in the usual mannerfrom a card, but it will be understood that the removal of the fibersmay be made directly from the card cylinder or other suitable sourcewithout the interposition of a dofier if desired.

In the description which follows, the method of producing the web is setforth in detail and the equipment for carrying out the method isillustrated in the drawings forming part of this disclosure. It is to beunderstood that this disclosure is illustrative and not restrictive asobvious variations from this disclosure within the scope of theinvention may be made.

In the drawings:

Figure 1 is a view in side elevation showing the feed-in roller, thecard, the dofier, the duct for removing the fiberfrom the doffer, andthe fiberreceiving and web-forming screen.

Figure 2 is a sectional View of the equipment shown in Figure 1 with theweb bonding instrumentalities and the web-drying equipment added.

Figure 3 is a view in plan showing the dofier, the duct,.thefiber-receiving screen, the spraying chamber, and the web-receivingroller, the driving gears for operating the parts being shown.

Figure 4 is an enlarged detail view, substantially on the line 4--4 ofFigure 3, showing a portion of the dofier, the air duct which removesthe fibers from the doifer, and the screen cylinder to which the fibersare delivered and on which the web is formed.

Figure 5 is a longitudinal sectional view of the web-forming screen onsubstantially the line 5-5 of Figure 4.

Figure 6 is a cross sectional view on substantially the line 6-4 ofFigure 5.

Figure 7 is a detail view showing the end of the screen housing. 7

Figure 8 is a detail view substantially on the line 8--8 of Figure 4.

Figure 9 is a sectional view substantially on the line 99 of Fi ure 4.

Figure 10 is a view substantially on the line Ill-Ill of Figure 4.

Figure 11 is a detail view substantially on the line ll-H of Figure 9.

Referring to the drawings by numbers, the same numbers designating thesame parts in the several views, and considering first the disclosuresin Figues 1 and 2, the frame 10, of any suitable or usual construction,carries the lap H, the feed roller l2, the taker-in I6, and the cardcylinder H, as in the usual carding engine cnstructi0n. These parts areall driven from any suitable source of power, a motor l8 being hereshown from which power is supplied to drive the variousinstrumentalities through suitable belting and gears. This being theusual construction of carding engines, further detailed description ofit is not necessary.

Adjacent the card cylinder I1 is a dofi'er 20, this doffer being drivenfrom the card cylinder by means of the cross belt 2|, the pulley 22, andthe doffer belt 23, so as to revolve the doifer in the direction of thearrow oposite from the direction of rotation of the card cylinder H. Inthe ordinary carding engine, the doifer rotates at a speed which isnormally from 3 to 18 R. P; M., thus producing an attenuation or draftfrom 90 to 140 on the stock, with draft being defined as the peripheralspeed of the clutter divided by the peripheral speed of the feed-inroll. In carrying out the present method, however, it has been foundthat the speed of the doffer must be higher relative to the speed of thefeed-in roll and the card cylinder, and drafts from 500 to 1500 arenecessary, a mean of 980 having been found to be a satisfactory draft,although it will be understood that the draft may be varied to someextent from the preferable mean. As a result of this range of highdrafts, the card cylinder deposits the fibers on the doffer in acompletely separated condition with each fiber being separate from theothers and not gathered together in groups, bunches, or clumps of manyfibers as are ordinarily present in equipment of this charcter when lowspeed dofling instrumentalities are used, so the fibers are laid on thedoffer in an evenly distributed, well separated manner.

On the side of the doifer opposite its contact point with the card isprovided a fiber transfer air duct 25, preferably of uniform dimensionthroughout its length, the doifer end of the duct 25 being placed inclose relation to the teeth of the dofier and preferably the duct 25will be slightly above the horizontal center of the doifer roll, asshown in Figure 2. It is desirable that the duct 25 which constitutes aconfined uninterrupted path be of equal area in cross section throughoutits length in order that there may be a uniform and even flow of air andfiber through the duct and turbulence caused by cross currents or swirlswhich might affect proper transmission of the fibers through the duct ifit was of varying cross section, are avoided. The duct 25 may beprovided, preferably on its upper side, with an air inlet 26, whichinlet may be regulated by means of a gate 21 adjusted in any suitablemanner as by the adjusting screw 28, so as to vary the size of the inlet26 as may be desired. The duct 25 may be constructed in any suitablemanner and is supported by means of a frame 29 secured to supportingside plates 30 mounted at one end on the dofler frame and at the otherend on the screen housing, presently to be described. The ductsupporting frame 29 may be provided with transparent panels 3|,preferably at its upper side in order that the flow of fiber through theduct may be observed and, if necessary, regulated by adjustment of theair inlet.

The delivery end of the duct 23 passes through a housing 32 having upperand lower sections in which is mounted a foraminous receiving surface,here shown as a revolving cylindrical screen 33 to which the ductdelivers, the screen 33 being mounted to revolve on a fixed shaft 34.Screen 33 is driven by a pinion 35 carried on the shaft of gear 36,which gear 38 engages gear teeth on the screen cylinder, as shown inFigure 1. Gear 36 is driven by the gear 31 on pulley 38 belted by belt39 to a gear assembly 40 driven from the motor 4!. The gear assembly 40is made up of a gear box having provision for interchanging the gears tovary speeds in the usual manner of changeable speed gear boxes.Interiorly of the screen 33 is a fixed shield 42 supported by shaft 34and having an air-receiving opening 43 in line with the delivery end ofthe duct 25, as shown in Figure 4, and through which opening 43 theblast of air passes after it has deposited the fibers on the screen 33.The fixed shield 42 prevents any disturbance of the web laid upon thescreen, the air being drawn out of the shield through exhaustconnections 44 which open at their upper ends into the shield and thelower ends of which engage a fan casing 45 having a fan 46,conventionally shown, which fan is driven from any suitable source ofpower and creates a strong suction through the escape passage 44; theduct 25, and the air inlet 26. The air current created by the fan stripsthe fibers directly from the dofier 20, the usual doifer comb beingdispensed with, and carries them in suspended and separated conditionthrough the duct and deposits them on the screen 33. The speed ofrotation of the screen may be varied through the change gear box orassembly 40 so as to give difierent screen speeds. By varying the speedof the screen, the thickness of the web formed by the fibers depositedon the screen may be widely varied. If a thin web is desired, the screencylinder will be revolved at relatively high speed so that a thin layerof fibers is deposited on it. If a thicker web is desired, the speed ofthe screen may be slowed down and a thicker web results.

The delivery end of the duct 25 will be sealed off from the screen inany suitable manner as for example, by the flexible seals 41', as shownin Figure 4, or by means of the sealing oif roller 48, which sealing of!roller is mounted for free revolution by reason of its contact with thescreen surface, this roller being preferably mounted in an adjustablespring mounting 49, as shown in Figures 9 and 11, so that its tensionagainst the screen surface may be varied.

The screen 33, which is mounted to revolve on the fixed shaft 34, iscarried by the spokes mounted on the hub 5| and driven by the gear 36.It is essential that the screen be sealed off from the housing againstthe entry of air and this is accomplished, as shown in Figure 5, byproviding sealing strips 32 carried by the housing 32, these stripseffectually preventing the entrance of air to the interior of thescreen.

The shield 42 is supported by the spokes 53 carried by the hub 54 whichis pinned to the shaft 34 so as to hold the shield 42 in fixed p sition.The shield 42 is sealed oi! at its ends from the screen 33 by thesealing strips 55 so as to confine the suction through the shield andpermit its escape only through the connections 44.

In the form of the invention shown in Figure 1, the machine is set toform a narrow fabric or sliver, which sliver is dolled from therevolving screen 33 by means of a dofling roll 56, as shown in Figure 1,driven from pinion 35, from which doffing roll it passes to thedrawing-off rolls 5! driven from any suitable source, and then passes toa sliver-receiving head 58, from which it is deposited in a sliver can59.

In Figure 2, the machine is shown with means for bonding the web withany suitable bonding solution. Any convenient or desired bondingequipment can be used. As here shown, it comprises a supporting stand 60having at its upper end a housing 6i in which are disposed spray headsconnected to a pipe 62, which pipe may be supplied from any suitablesource with the bonding solution. The web will be removed from thescreen cylinder 33 and brought to the bonding area by a belt 83 mountedon rollers driven from any suitable source of power, so that, as thebelt is driven, the web will be carried forward to dryinginstrumentalities hereinafter described. The belt may be formed of anysuitable flexible and porous material such as cloth, woven wire, and thelike. Any suitable means such, for example, as suction tube 65 may beprovided to draw the bonding solution through and thoroughly impregnatethe web. Any excess solution from the belt 63 will be caught by adrainage shelf 63 having a discharge tube 64' through which excesssolution or overflow from the belt 63 will be delivered to any suitablereceptacle.

The web passes from the belt 63 to drying and curing means as shown inFigure 2. This drying and curing equipment may be made up in differentways, but is here shown as an electrical dryer. It comprises a stand 66having a heated box B1 in which is mounted for rotation rollers 68having a carrier belt 69 to which the web is delivered from the belt 63.Heating and drying elements Hi, conventionally shown as electricalheating elements to which current is supplied from any suitable source,are disposed above and below the belt 69 so that the web is subjected tocomplete drying and curing and then passes over a roller ii and isdelivered in bonded and dried condition.

Following the method and usingthe equipment herein shown and described,a non-woven fabric characterized by uniform density and texture and ofequal strength in all directions, free from imperfections caused byknots and tangles, and of superior appearance ray be produced.

Such variations from the specific construction here shown and describedas involve only mechanical skill and are comprehended by the appendedclaims are to be regarded as within the range of the invention.

We claim:

1. The method of forming non-woven fabrics which comprises cardingfibres and thus continuously providing a source of fibre supply ofcarded fibres, continuously delivering the said carded fibres from asupply to a foraminous fibre receiving member to form on such member aweb, said delivery being accomplished by passing the carded fibres fromsaid supply to the foraminous member by means of an air current througha confined uninterrupted path of equal area in cross section throughoutits length, the fibres being suspended in said air current during travelin said path to the foraminous fibre receiving member, forming a web onsaid member, and removing the web from said member.

2. The method of forming non-woven fabrics which comprises cardingfibres and thus continuously providing a source of fibre supply ofcarded fibres, continuously delivering the said carded fibres from asupply to a foraminous fibre receiving member to form on such member aweb, said delivery being accomplished by passing the carded fibres fromsaid supply to the foraminous member by means of an air current througha confined uninterrupted path of equal area in cross section throughoutits length, the fibres being suspended in said air current during travelin said path to the foraminous fibre receiving member, forming a web onsaid member, removing the web from said member, and bonding the web.

3. The method of forming non-woven fabrics which comprises cardingfibres and thus continuously providing a source of fibre supply ofcarded fibres, continuously delivering the said carded fibres from asupply to a foraminous fibre receiving member to form on such member aweb, said delivery being accomplished by passing the carded fibres fromsaid supply to the foraminous member by means of an air current througha confined uninterrupted path of equal area in cross section throughoutits length, the fibres being suspended in said air current during travelin said path to the foraminous fibre receiving member, forming a web onsaid member, removing the web from said member, bonding the Web, anddrying the Web.

4. The method of forming a fibrous web which comprises carding fibres ata draft of at least 500 and thus continuously providing a source offibre supply of carded fibres, continuously delivering said cardedfibres from a supply to a foraminous fibre receiving member to form onsuch member a web, said delivery being accomplished by passing thecarded fibres from said supply to the foraminous member by means of anair current through a confined uninterrupted path, the fibres beingsuspended in said air current during travel in said path to theforaminous fibre receiving member, forming a web on said member, andremoving the'web from said member.

5. The method according to claim 4 wherein said path is of equal area incross section throughout its length.

6. As a new article of manufacture a nonwoven fabric formed of randomlaid fibres matted together in uniform relation and characterized byfreedom from knots and tangles and of uniform density and strength inall directions, and prepared by the method of claim 1.

7. As a new article of manufacture a nonwoven fabric formed of randomlaid fibres matted together in uniform relation and characterized byfreedom from knots and tangles and of uniform density and strength inall directions, and prepared by the method of claim 2.

8. As a new article of manufacture a nonwoven fabric formed of randomlaid fibres matted together in uniform relation and characterized byfreedom from knots and tangles and of uniform density and strength inall directions, and prepared by the method of claim 3.

9. As a new article of manufacture a non- ,woven fabric formed of randomlaid fibres matted together in uniform relation and characterized byfreedom from knots and tangles and of uniform density and strength inall directions, and

Name Date Moss May 14, 1935 Rogers Feb. 7, 1939 Smith June 3, 1941 KaneMar. 5, 1946 FOREIGN PATENTS Country .Date Great Britain June 19, 1924Great Britain Aug. 14, 1924 Great Britain June 5, 1942

